Automate Screenshots on iPhone Simulator?

Question

I\'m tired of taking new screenshots everytime I change my UI for my iPhone application. I would like to be able to run a script/program/whatever to load my binary on the si

Answer 1

I have the same wish. I want to be able to save screenshots from a few screens in my app without all the manual work. I'm not there yet, but I have started.

The idea is to tail /var/log/system.log, where the output from the NSLog statements go. I pipe the output to a python program. The python program reads all the lines from stdin and when the line matches a specific pattern, it calls screencapture.

NSLog(@"screenshot mainmenu.png");

That will cause a screenshot named "XX. mainmenu YY.png" to be created every time it is called. XX is the number of the screenshot since the program started. YY is the number of the "mainmenu" screenshot.

I have even added some unnecessary features:

NSLog(@"screenshot -once mainmenu.png");

This will only save "XX. mainmenu.png" once.

NSLog(@"screenshot -T 4 mainmenu.png");

This will make the screenshot after a delay of 4 seconds.

After running an app with the right logging, screenshots with the following names could have been created:

00. SplashScreen.png
01. MainMenu 01.png
03. StartLevel 01.png
04. GameOver 01.png
05. MainMenu 02.png

Give it a try:

1. Add some NSLog statements to your code

2. $ tail -f -n0 /var/log/system.log | ./grab.py

3. Start your iPhone app in the Simulator

4. Play around with your app

5. Have a look at the screenshots showing up where you started the grab.py program

grab.py:

#!/usr/bin/python

import re
import os
from collections import defaultdict

def screenshot(filename, select_window=False, delay_s=0):
    flags = []
    if select_window:
        flags.append('-w')
    if delay_s:
        flags.append('-T %d' % delay_s)
    command_line = 'screencapture %s "%s"' % (' '.join(flags), filename)
    #print command_line
    os.system(command_line)

def handle_line(line, count=defaultdict(int)):
    params = parse_line(line)
    if params:
        filebase, fileextension, once, delay_s = params
        if once and count[filebase] == 1:
            print 'Skipping taking %s screenshot, already done once' % filebase
        else:
            count[filebase] += 1
            number = count[filebase]
            count[None] += 1
            global_count = count[None]
            file_count_string = (' %02d' % number) if not once else ''

            filename = '%02d. %s%s.%s' % (global_count, filebase, file_count_string, fileextension)
            print 'Taking screenshot: %s%s' % (filename, '' if delay_s == 0 else (' in %d seconds' % delay_s))
            screenshot(filename, select_window=False, delay_s=delay_s)

def parse_line(line):
    expression = r'.*screenshot\s*(?P-once)?\s*(-delay\s*(?P\d+))?\s*(?P\w+)?.?(?P\w+)?'
    m = re.match(expression, line)
    if m:
        params = m.groupdict()
        #print params
        filebase = params['filebase'] or 'screenshot'
        fileextension = params['fileextension'] or 'png'
        once = params['once'] is not None
        delay_s = int(params['delay_s'] or 0)
        return filebase, fileextension, once, delay_s
    else:
        #print 'Ignore: %s' % line
        return None

def main():
    try:
        while True:
            handle_line(raw_input())
    except (EOFError, KeyboardInterrupt):
        pass

if __name__ == '__main__':
    main()

Issues with this version:

If you want to take a screenshot of only the iPhone Simulator window, you have to click the iPhone Simulator window for every screenshot. screencapture refuses to capture single windows unless you are willing to interact with it, a strange design decision for a command line tool.

Update: Now iPhone simulator cropper (at http://www.curioustimes.de/iphonesimulatorcropper/index.html) works from command line. So instead of using the built in screencapture, download and use it instead. So now the process is completely automatic.